As a new Congress takes over on Capitol Hill, all eyes are turning to what will certainly be a vastly different Obama Cabinet in the coming weeks.

High-level vacancies in the administration are expected to include secretary of state, secretary of defense and treasury secretary. A permanent CIA director also must be chosen.

And even though President Barack Obama remains on vacation all week in Hawaii, 5,000 miles away from Washington, speculation is swirling over whom Obama will pick for the top spots and when they will be announced.

Although Obama announced late last month that Sen. John Kerry is his pick to replace Hillary Clinton as secretary of sate, a senior administration official tells CNN no final decisions have been made regarding the other key positions.

CNN has learned that former Republican Sen. Chuck Hagel, a top contender for the Defense Department post whose prospects had appeared to be dimming amid criticism from pro-Israel groups and gay organizations over past comments, is still in the running for secretary of defense.

Another source tells CNN’s Gloria Borger that the president “hasn’t signed off yet” on Hagel replacing outgoing Defense Secretary Leon Panetta and is “mulling over this and other appointments” while in Hawaii this week.

The general expectation, this source added, is that the president will likely announce the Defense post, as well as other Cabinet appointments, as early as next week.

Hagel has some big backers.

“I understand his nomination is back on the table, and I believe very strongly he should be defense secretary,” former Democratic Sen. Max Cleland told CNN.

Meanwhile, the president himself did not rule Hagel out for the top Defense post in a recent interview on NBC’s “Meet the Press.”

“My No. 1 criteria will be who’s going to do the best job in helping to secure America,” the president said, adding that nothing he had seen specifically ruled Hagel out.

Still, Hagel supporters are concerned about the process of names being floated and opening possible contenders up to harsh scrutiny before they are formally named.

“Anyone with any record of involvement in controversial issues will always mobilize against a would-be nominee a whole phalanx of accusations and sometimes distortions,” said Zbigniew Brzezinski, the former national security adviser to former President Jimmy Carter.

Hagel is not the only name in the mix for the powerful post. Michele Flournoy, former undersecretary of defense for policy, remains a leading candidate. A source also tells Borger that Deputy Defense Secretary Ash Carter “still has his supporters.”

Meanwhile, at the Treasury Department, where Secretary Timothy Geithner plans to leave sometime around the inauguration, at least one person floated — American Express CEO Kenneth Chenault – has no plans to leave that company, a spokesman confirmed to CNN.

White House Chief of Staff Jack Lew is considered to be a frontrunner for the job.

At the CIA, Counterterrorism and Homeland Security Adviser John Brennan and Acting CIA Director Michael Morrell remain on the short list to replace retired Gen. David Petraeus, according to a source.

History shows that most presidents get the nominees they want, but in this political environment, there’s no guarantee.

“It used to just be Supreme Court justices who inspired these sorts of partisan free-for-alls; now it’s bleeding into a president’s cabinet picks as well,” said Reid Wilson of the National Journal.